Our car is running Zetec 1800 on a NoDiz Pro.

The previous owner looks to have had some issues getting the rev counter calibrated properly as the feed from the NoDiz is running under the dash but terminated with tape, an additional wire has been run to the alternator.

The Rev Counter is a Caerbont Automotive Instruments 80mm Semi-Programmable model. The manual is attached.

When I first looked at the rev counter the settings were set to a 6 cylinder not 4, the rev counter showed a correct idle speed but when revved it was way out. I set the rev counter to 4 cylinder and it now idles very high with the lowest it can be calibrated to is 1800rpm, revving the engine the counter goes off the clock.

I am not sure of the origin of the alternator and am assuming it is not compatible with the rev counter.

Plugging in the nodiz signal the counter does nothing, I have placed a multimeter on the nodiz signal in AV Voltage mode and it is registering approx 0.3v at idle. It does raise slightly on revving the engine but then drops back down.

I am not electrically minded so not sure what the next course of action should be.

Any suggestions are welcomed.

https://drive.google.com/file/d/14y21Xzqdp5o1a4wm0pLraqLqQEZsE XsV/view?usp=sharing

Is it possible to set the Rev counter to 2 cylinders? 1800 RPM at idle it’s reading double probably due to wasted spark?

It only has options for 4, 6 and 8 cylinders.

Could you not use a single HT Wire as the Pick Up point?

Also, Have you tried 8 Cylinders?
It will divide 1800 by two. (I think) as it will need twice as many pulses to register one revolution.

if you are using it in alternator mode. (sw3 off: usually just for diesel ) there is a potentiometer on the back for adjustment.

you should be using it in standard mode, sw3 on, sw5 on, and probably sw4 off. if it doesn't register, then sw4 on.
4 cyl even with lost spark is just 2 pulses per revolution. (sw1&2) off

ie feed it from nodiz with switches
1 off
2 off
3 on
4 tbd prob off
5 on

Thanks but I have tried every conceivable combinations of switch settings, when set to 4 Cylinders and ECU/Alternator the adjustment on the back allows the revs at idle range from 1800min and 7000max.

We are thinking the nodiz is faulty on that pin as it doesnt seem to be sending a signal.

My limited understanding of taking a signal from the alternator is it only works if the pulses and pulley revs are all in sync?

I did wonder if we can take a signal from the coil pack? Its running a standard zetec pack.

The manual suggests the RED/BLUE wire can go to the low tension side of the coil.

yes take it from the lt side of one coil.
the reason the nodiz output looks low, is its a 'digital' output, also it may need a pull-up resistor.